Both the ZKK-602 the CZ-550 have set triggers, unless you got them replaced/modified.
The only major difference is the direction the safety travels, other then that it's just cosmetic. The older 602 has a bolt shroud that is very similar in appearance to the Remington M-700. Personally I prefer the looks of the ZKK-602 but the safety on the CZ-550, because it's basically exactly like the Rem M-700.
Btw, I have one of each.